80 THE WHENCE AND THE WHITHER OF MAN 



careful consideration. The swimming life would ap- 

 pear to be neither as easy nor as economical as the 

 creeping. It is certainly hard to believe that food 

 would not have been obtained with less effort and in 

 greater abundance at the bottom than in the water 

 above. The swimming life gave rise to higher and 

 stronger forms ; but did its maintenance give imme- 

 diate advantage in the struggle for existence ? This 

 is an exceedingly interesting and important question, 

 and demands most careful consideration. But we 

 shall be better prepared to answer it in a future lect- 

 ure. 



The period of development of mollusks, articu- 

 lates, and vertebrates, is really one. They developed 

 to a certain extent contemporaneously. The develop- 

 ment of vertebrates was slow, and they were the last 

 to appear on the stage of geological history. 



You must all have noticed that development, during 

 this period, takes on a much more hopeful form than 

 during that described in the last chapter. Then diges- 

 tion and reproduction were dominant. Now muscle 

 is of the greatest importance. If this fails of devel- 

 opment, as in mollusks, the group is doomed to de- 

 generation or at best stagnation. But we have seen 

 the dawn of a still higher function. In insects and 

 vertebrates the braiu is becoming of importance, and 

 absorbing more and more material. This is the prom- 

 ise of something vastly higher and better. Better 

 sense-organs are appearing, fitted to aid in a wider 

 perception of more distant objects. The vertebrate 

 has discovered the right path ; though a long journey 

 still lies before it. The night is far spent, the day is 

 at hand. 



